1. Field
This disclosure relates generally to MEMS devices, and more specifically, to a method of anti-stiction dimple formation under MEMS.
2. Related Art
Micromachined Electrical Mechanical Switches (MEMS) suffer from a phenomenon referred to as ‘stiction’ in MEMS devices. Stiction occurs when the microstructure of the MEMS device is brought to an ‘intimate contact’ with a surrounding surface. Once in contact, Van der Waals force or hydrogen bonding on the surface exceeds the restoring spring force of the MEMS structure, undesirably resulting in a permanent stiction. In addition, such a stiction bonding force increases as the contact area increases.
Dimples under MEMS devices are known in the art; however, the methods of creating dimples are different. For example, in one method, dimples have been made by a patterning and etching of dimple material used to form dimple contact areas. However, such direct patterning and etching of the dimple material results in dimples larger than desired or useful. In another method, dimples are formed on springs for an SOI based optical MEMS; however, such a method does not provide a method to create dimples under an SOI MEMS structure. In yet another method, dimples are created by depositing polysilicon after a partial release of the MEMS structure. The later method is undesirable, as it requires extra processing steps for dimple formation.
Accordingly, there is a need for an improved method and apparatus for overcoming the problems in the art as discussed above.